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Range and Habitat: Eastern Pacific shallow coasts, also
east Indian Ocean, but none in the central Pacific. Monterey Bay
to the southern coasts of Mexico and Chile. They prefer rocky
algae-covered habitats, and are tropical, temperate and benthic
(live on the bottom).
Description: Flat, broad head; short snout; large mouth
with sharp, pointed teeth; brown blotches, spots or yellow-brown
body with young lighter in color. They have a long mouth that
extends behind their eyes, an anal fin and two spineless dorsal
fins. They have nictitating lower eyelids with unique muscles.
Swell shark teeth are small cuspidate or flattened to large and
bladelike. Swell sharks reach up to three and a half feet in length.
They range in size up to 3 1/2 feet.
Habits and Adaptations: Gulps water or air to inflate
belly and wedges itself into rocks. When expelling air, it makes
a dog-like bark. Rest in caves and crevices, wedges and swells.
Ambushes fish or hangs out with mouth agape and waits for an unsuspecting
meal.
Diet: Mollusks and crustaceans, hunts fish and invertebrates
at night.
Breeding and Maturation: Males have siphon sacs that pump
seawater to aid the flow of semen from claspers. Oviparous. Females
lay two greenish-amber eggs at a time. These egg cases are often
called ‘mermaid’s purses’ with tendrils that entangle
among plants, rocks or coral to keep them in a safe place. These
embryos develop in the cases for one year, feeding on yolk, and
once they hatch they are instantly ready to eat mollusks and crustaceans.
Water temperature determines incubation (7.5-10 months), and hatchlings
are 6 inches in length. They hatch by using two rows of enlarged
dermal denticles along their back which shed shortly after hatching.
Miscellaneous: Swell sharks are members of the catshark
family, and are not considered dangerous. They are among the largest
group of sharks, with 197 known species. They are related to blue,
silky and oceanic whitetip sharks. They have been a subject of
electroreception studies, and flee rather than attack (from humans).
These sharks are aggressive only when stepped on, and inflict
only a superficial wound. Swellshark egg cases are often preyed
upon by snails.
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